1. Field of the Invention
This invention relates to agricultural and horticultural fungicidal compositions, and more particularly to such fungicidal compositions containing at least one kind of known fungicidal compounds and N-(4-flurophenyl)-2,3-dichloromaleimide.
2. Description of the Prior Arts
One of the most serious problems that is encountered in culture of agricultural products is diseases. Various kinds of compounds such as organic metal compounds, chlorine compounds, antibiotics, etc., have been proposed and practically used as preventive agents against such disease. Neverthless, any of these compounds involves many problems in respect of antimicrobial spectrum, efficacy, toxicity, retention, damage from use of compounds and other matters, and some of these compounds have been condemned as more harmful than beneficial. Thus, strong request is voiced for development of a fungicide which is free of these problems.
Among the commercially available fungicides, the metal-containing ethylenebisdithiocarbamate compounds present an antimicrobial spectrum that shows high effect against gummy stem blight, anthracnose, alternaria leaf spot, melanose, ripe rot and other similar kinds of diseases which attack such plants as cucumber, tomato, melon, citrus fruits, apple, persimmons and grapes, but these compounds are poor in effect against scab and black rot of citrus fruits and gray leaf spot of tomato. On the other hand, N-trichloromethylthio-4-cyclohexene-1,2-dicarboxyimide or 8-oxyquinoline copper presents an antimicrobial spectrum demonstrating strong efficacy against anthracnose, leaf mold, scab, black spot and ripe rot which develop on cucumber, tomato, melon, apple, pear, grape and other like fruit trees, but such compounds are poorly protective against alternaria leaf spot of applies and melanose of citrus fruits. Also, some of these compounds could produce bad damage to the crops. N-(4-fluorophenyl)-2,3-dichloromaleimide also presents a wide antimicrobial spectrum indicating high efficacy for a variety of plant diseases such as anthracnose, apple scab, citrus scab, etc., but this compound is weak in effect against downy mildew of cucumber and gray leaf spot of tomato, and it is impossible to prevent such diseases with a normal concentration (750 - 1,500 ppm). It needs to use the compound at a concentration of over about 1,500 ppm for obtaining a satisfactory effect against these diseases, but such high concentration could cause serious damage to the new leaves. Thus, in use of such compound, minute care is required in determining the time of use and concentration of the compound.
The present inventors found that a suitable combination of these per se defective compounds could produce a surprisingly high effect against melanose of citrus fruits, downy mildew of cucumber, gray leaf spot of tomato and mildew of apple which can hardly be controlled perfectly by single use of these compounds, and that such combination could bring about an excellent effect with a far lower concentration that the normal use level required in single use of said compounds. Thus, the fungicidal compositions provided according to this invention are capable of controlling almost all kinds of diseases that plague the agricultural and horticultural plants. These compositions are also worth notice in that they can greatly expand the scope of use of the fungicidal compounds and that the required concentration of the active compounds in practical use can be reduced by suitable blending of these compounds.